const CAuthCode = defineComponent({
  props: {
    id: {
      type: String,
      required: true
    },
    identifyCodeMax: {
      type: Number,
      default: 4
    },
    identifyCode: {
      type: String,
      default: '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXY'
    },
    fontSizeMin: {
      type: Number,
      default: 25
    },
    fontSizeMax: {
      type: Number,
      default: 30
    },
    backgroundColorMin: {
      type: Number,
      default: 255
    },
    backgroundColorMax: {
      type: Number,
      default: 255
    },
    colorMin: {
      type: Number,
      default: 0
    },
    colorMax: {
      type: Number,
      default: 160
    },
    lineColorMin: {
      type: Number,
      default: 100
    },
    lineColorMax: {
      type: Number,
      default: 255
    },
    dotColorMin: {
      type: Number,
      default: 0
    },
    dotColorMax: {
      type: Number,
      default: 255
    },
    dotMax: {
      type: Number,
      default: 40
    },
    contentWidth: {
      type: Number,
      default: 112
    },
    contentHeight: {
      type: Number,
      default: 31
    },
    onClick: Function
  },
  emits: {
    authCodeChange: (authCode: string): boolean => true
  },
  setup(props, {emit}) {
    // 生成一个随机数
    function randomNum(min: number, max: number) {
      return Math.floor(Math.random() * (max - min) + min)
    }

    // 生成一个随机的颜色
    function randomColor(min: number, max: number) {
      const r = randomNum(min, max)
      const g = randomNum(min, max)
      const b = randomNum(min, max)
      return 'rgb(' + r + ',' + g + ',' + b + ')'
    }

    function drawPic() {
      const canvas = document.getElementById(props.id) as HTMLCanvasElement
      const ctx = canvas.getContext('2d') as CanvasRenderingContext2D
      ctx.textBaseline = 'bottom'
      // 绘制背景
      ctx.fillStyle = randomColor(props.backgroundColorMin, props.backgroundColorMax)
      ctx.fillRect(0, 0, props.contentWidth, props.contentHeight)
      let text = ''
      // 绘制文字
      for (let i = 0; i < props.identifyCodeMax; i++) {
        const txt = props.identifyCode[Math.floor(Math.random() * props.identifyCode.length)]
        drawText(ctx, txt, i)
        text += txt
      }
      emit('authCodeChange', text)
      drawLine(ctx)
      drawDot(ctx)
    }

    function drawText(ctx: CanvasRenderingContext2D, txt: string, i: number) {
      ctx.fillStyle = randomColor(props.colorMin, props.colorMax)
      ctx.font = 'bold ' + randomNum(props.fontSizeMin, props.fontSizeMax) + 'px SimHei'
      const x = (i + 1) * (props.contentWidth / (props.identifyCodeMax + 1))
      const y = randomNum(props.fontSizeMax, props.contentHeight - 5)
      const deg = randomNum(-45, 45)
      // 修改坐标原点和旋转角度
      ctx.translate(x, y)
      ctx.rotate((deg * Math.PI) / 180)
      ctx.fillText(txt, 0, 0)
      // 恢复坐标原点和旋转角度
      ctx.rotate((-deg * Math.PI) / 180)
      ctx.translate(-x, -y)
    }

    function drawLine(ctx: CanvasRenderingContext2D) {
      // 绘制干扰线
      for (let i = 0; i < 5; i++) {
        ctx.strokeStyle = randomColor(props.lineColorMin, props.lineColorMax)
        ctx.beginPath()
        ctx.moveTo(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight))
        ctx.lineTo(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight))
        ctx.stroke()
      }
    }
    function drawDot(ctx: CanvasRenderingContext2D) {
      // 绘制干扰点
      for (let i = 0; i < props.dotMax; i++) {
        ctx.fillStyle = randomColor(props.dotColorMin, props.dotColorMax)
        ctx.beginPath()
        ctx.arc(
          randomNum(0, props.contentWidth),
          randomNum(0, props.contentHeight),
          1,
          0,
          2 * Math.PI
        )
        ctx.fill()
      }
    }
    watch(
      () => props.identifyCode,
      n => {
        drawPic()
      }
    )

    onMounted(() => {
      drawPic()
    })
    return () => (
      <div class='s-canvas cursor-pointer border-1 border-gray'>
        <canvas
          title='点击切换'
          id={props.id}
          width={props.contentWidth - 2}
          height={props.contentHeight - 2}
          onClick={() => {
            drawPic()
          }}
        ></canvas>
      </div>
    )
  }
})

export default CAuthCode
